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confused acoustic vs rf

Dear Concerned,

I like this article a lot, but I am also getting quite confused halfway through it, as it seems to jump back and forth between acoustic and RF chambers. It woudl help , I think, if they could be basically just split into two different sections completely. They could refer to the other, where there are similarities, but overall, the two different ppl reading this are gonna be people interested in sound recording, and people interested in RF testing... and so the different sections should focus on addressing those two aduiences separately imho.

I've rewritten things a little bit to hopefully clarify Richard☺Decal (talk) 03:48, 31 March 2017 (UTC)[reply]

etc

As an aviation enthusiast I've heard of anechoic chambers being used for radar signature measurement, where the echos absorbed are radar echos, not sound echos. Anechoic chambers for EM radiation should be mentioned in addition to ones meant for audio purposes.

I'll try to do a significant revision and addition to incorporate this. mnemonic 10:49, 2004 Jun 21 (UTC)

Should the words "dampening" and "dampened" be used? Doesn't that mean the panels are making something wet? ;)

Perhaps "damping" and "damped" should be used.

More here:

http://en.wikipedia.org/wiki/Dampening

Acoustic and RF (electromagnetic) anechoic chambers

I have added several paragraphs about RF anechoic chambers as opposed to acoustic ones and I have not as yet deleted anything. I think it improves the article but it could do with a tidy up, or perhaps it might be worth splitting it into the two different types. If nobody else does I'll get back to it in a few weeks.

I think some clarification is needed about the acoustic and RF wavelengths. It is true that a typical audio frequency of 500Hz acoustic wavelength (0.7 m) is very different from 500 Hz electromagnetic (600 km) but I don't think many RF tests are done as low as 500 Hz. But 0.7 m RF wavelength I make about 454 MHz. Many tests are done around these UHF frequencies. ChrisAngove 17:43, 10 November 2006 (UTC)[reply]

External links

Suggested Improvements

Picture of the interior of an RF anechoic chamber if possible showing something being tested. References to the particular international standards (a) that chambers are built to and (b) that are typically tested for in the chambers. A picture or two showing the shell construction ie. the screened room for the RF and the 'metre thick cement' or similar for the acoustic one. ChrisAngove 17:39, 18 November 2006 (UTC)[reply]

Acoustic Testing of Satellite Components

Does anybody know anything about the very high level acoustic noise testing that used to be done on components to go into space? I believe it may have been to similate launch conditions. Do they still do it or has it been superceeded? The levels would need a heavy duty chamber i think. ChrisAngove 17:39, 18 November 2006 (UTC)[reply]

Acoustic Anechoic chamber?

Why is all the information about acoustic anechoic chambers here in the discussion page rather than in the actual article? —The preceding unsigned comment was added by 67.64.252.71 (talk) 20:41, 13 May 2007 (UTC).[reply]

Advertisement?

Reference 1 to the TDK RF solutions page seems to lead to a commercial website providing absorption solutions, without really benefiting the article.46.144.116.121 (talk) 09:47, 6 August 2014 (UTC)[reply]

semi or hemi anechoic

Hi,

I think it would be of interest of many people to add a chapter about semi and hemi anechoic chambers with regard to the different measurement possibilities. —Preceding unsigned comment added by 82.210.249.81 (talk) 09:56, 6 December 2007 (UTC)[reply]

Quick reply to this - Semi-anechoic is used to describe RF chambers. I think hemi describes acoustic, but I have no experience with those. I have never heard hemi used in relation to RF chambers - EMC enginer —Preceding unsigned comment added by 66.41.160.226 (talk) 01:25, 14 February 2008 (UTC)[reply]

partly wrong

the whole RAM-section contained factual errors, and had no citations or sources: (ferrite plates vs. pyramid shaped is just completely wrong since i know that the ferrite plates are less effective at HIGHER frequencies) source: I found a ferrite plate damping curve, but there might be other/better sources.

There might be more factual errors, since large parts of this article remain unverified.

—Preceding unsigned comment added by 194.116.159.61 (talk) 13:13, 21 January 2008 (UTC)[reply]

Caves?

Mention if caves are good Anechoic chambers, at least electronically. Jidanni (talk) 02:26, 22 February 2009 (UTC)[reply]

Acoustic anechoic chambers

Is this right: "In general, the interior of an anechoic chamber is very quiet, with typical noise levels in the 10-20 dBA range." The University of Salford has a semi-anechoic chamber with only 3.8dba background noise, so this seems hard to believe. Also, the University of Salford claims an anechoic chamber with a -12.4dBA background noise level, so perhaps this Guinness record needs updating. I don't really know anything about this topic, but a quick google search yielded these. Anybody know more about this? NeverWorker (Drop me a line) 03:27, 29 July 2009 (UTC)[reply]

The "in general" phrase is correct. Few chambers go lower than 10dBA. The dBA measurement is relatively insensitive to low frequencies, so a low dBA number might be hiding a degree of low frequency rumble. 0dBA is 20 micropascals, or the lowest level a human can hear. Going lower than zero dBA is a very rare achievement. Binksternet (talk) 04:01, 29 July 2009 (UTC)[reply]

A thing I think is missing from the article, is the effect is has on humans. Not only is it quiet; it is so quiet that you can hear the blood run in your veins. The first time I experienced this was in an anechoic sound studio in NRK Marienlyst in Norway. It made me feel quite disconcerted, and some of the women freaked out and got claustrophobia. Also, sounds from others were dampened quite a bit since no sound was allowed to echo, so you felt like you had to yell to be heard even if somebody was right next to you. 80.203.35.234 (talk) 02:21, 7 April 2013 (UTC)[reply]

Does this have the frequency culprit reversed???

The sentence: "Such risks are from RF or non-ionizing radiation and not from the higher energy ionizing radiation." DOES THAT have the culprit reversed? 68.121.32.86 (talk) 23:03, 29 June 2013 (UTC)[reply]

It is correct. Risks from high levels of non-ionizing RF include heating (burning or cooking) and electric shocks. It can also affect objects carried such as watches, spectacle frames and heart pacemakers. — Cheers, Steelpillow (Talk) 12:23, 25 October 2015 (UTC)[reply]

Effect on people remaining within room

No mention of how it produces an unsettling effect and the longest anyone's stayed in one is 45 minutes? Really? — Preceding unsigned comment added by 162.157.42.210 (talk) 05:20, 26 May 2014 (UTC)[reply]

Me thinks what the article so far has to say about that is quote off: "Anecdotally, some humans may not like such quietness and can become disoriented." It is not anecdotally that it is unsettling. Though I found no medical or otherwise scientific article or research about that per se, it is mentioned in this article: http://www.odditycentral.com/news/worlds-quietest-place-lets-you-hear-your-internal-organs.html :
"as it turns out people can’t stand to be in the world’s quietest place for too long. The longest a person has lasted in there is 45 minutes. [...] The room gets so silent that you can actually hear your internal organs at work. And after a while, the hallucinations begin. [...] The founder and president of Orfield Labs, Steven Orfield says that people are challenged to sit in the chamber with all the lights out. There was this one reporter who managed to stay in there for 45 minutes. Mr. Orfield himself can do it for 30 minutes, in spite of his mechanical heart valve that becomes very loud inside the room. «When it’s quiet, ears will adapt,» he says. «The quieter the room, the more things you hear. You’ll hear your heart beating; sometimes you can hear your lungs, hear your stomach gurgling loudly. In the anechoic chamber, you become the sound.» The experience is so disorienting that it could drive a person mad. In fact, it is imperative that people sit down. Standing up and walking around is simply impossible. Because we orient ourselves through the sounds we hear when we walk, there are no cues to go by inside the chamber. «You take away the perceptual cues that allow you to balance and maneuver. If you’re in there for half an hour, you have to be in a chair,» Mr. Orfield says." (emphasis by me) And this is about the -9dB room, not the -21dB room.

So, not being able to stand for a mere 30 minutes, even suggesting people sit down as quick as possible (" it is imperative that people sit down. Standing up and walking around is simply impossible. Because we orient ourselves through the sounds we hear when we walk") sounds so much more factual than just what the article so far says, as quoted above. ("Anecdotally, some humans may not like such quietness and can become disoriented"). So, while I only found this article on that, and even less info in http://www.mprnews.org/story/2012/04/03/daily-circuit-quiet-room it still, to me, is enough factual data to remove the above quote and insert more about the factual disorienting experience, especially in the dark, also when combined with the everyday action of standing and walking around. Dietmar Lettau (talk) 17:45, 23 August 2016 (UTC)[reply]

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+{{WikiProject banner shell|class=C|vital=yes|1=
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 ===confused acoustic vs rf===
@@ Line 6: / Line 9: @@
 I like this article a lot, but I am also getting quite confused halfway through it, as it seems to jump back and forth between acoustic and RF chambers. It woudl help , I think, if they could be basically just split into two different sections completely. They could refer to the other, where there are similarities, but overall, the two different ppl reading this are gonna be people interested in sound recording, and people interested in RF testing... and so the different sections should focus on addressing those two aduiences separately imho.
+: I've rewritten things a little bit to hopefully clarify [[User:Richard.decal|Richard☺Decal]] ([[User talk:Richard.decal|talk]]) 03:48, 31 March 2017 (UTC)
 === etc ===
@@ Line 28: / Line 33: @@
 I think some clarification is needed about the acoustic and RF wavelengths. It is true that a typical audio frequency of 500Hz acoustic wavelength (0.7 m) is very different from 500 Hz electromagnetic (600 km) but I don't think many RF tests are done as low as 500 Hz. But 0.7 m RF wavelength I make about 454 MHz. Many tests are done around these UHF frequencies. [[User:ChrisAngove|ChrisAngove]] 17:43, 10 November 2006 (UTC)
+== External links ==
-==Substantial Changes==
+===Suggested Improvements===
-After a common introduction I have tried to separate out the anechoic and RF versions. I have not intentionally deleted any of the previous factual information. This is the original:
-***
+Picture of the interior of an RF anechoic chamber if possible showing something being tested.
-[[image:anechoic_chamber.jpg|thumb|200px|A picture of an anechoic chamber]]
+References to the particular international standards (a) that chambers are built to and (b) that are typically tested for in the chambers.
-An '''anechoic chamber''' is a room that is isolated from external [[sound]] or electromagnetic radiation sources, sometimes using [[sound proofing]], and prevents the reflection of wave phenomena ([[reverberation]]). In rooms such as these, the only sounds which exist are emitted directly from their source, and not reflected from another part of the chamber. Anechoic rooms have the characteristic of being muted, muffled, and silent. Anechoic chambers are widely used for measuring the [[acoustics|acoustic]] properties of acoustic [[Musical instrument|instrument]]s, measuring the [[transfer function]]s of electro-acoustic devices, testing [[microphone]]s and performing [[psychoacoustics]] experiments (such as measuring the quality of audio [[codec]]s or measuring [[head-related transfer function]]s).
+A picture or two showing the shell construction ie. the screened room for the RF and the 'metre thick cement' or similar for the acoustic one.
+[[User:ChrisAngove|ChrisAngove]] 17:39, 18 November 2006 (UTC)
+===Acoustic Testing of Satellite Components===
-Anechoic chambers, modeled after the world's first wedge-based anechoic chamber at [[Murray Hill, New Jersey|Murray Hill]], [[Bell Labs]], typically use [[fiberglass]] wedges ([[Anechoic tile]]) on all walls of the chamber to absorb incoming sound waves.  The wedge shape acts as a [[waveguide]] to focus incoming sound into the fiberglass wedge, where the acoustic energy is converted to heat.  The alternating pattern is used to achieve a more uniform angular absorption.  Frequencies below 200 [[Hertz|Hz]] are not as effectively absorbed by the wedges.
+Does anybody know anything about the very high level acoustic noise testing that used to be done on components to go into space? I believe it may have been to similate launch conditions. Do they still do it or has it been superceeded? The levels would need a heavy duty chamber i think.
-Anechoic chambers in which the bottom is also composed of wedges have the floor formed by a wire mesh suspended above the bottom by wires.  Other anechoic chambers only use wedges for five of the six sides of the room.  To prevent external sounds from entering anechoic chambers, most are encased in a meter or more of cement and may be surrounded by additional insulating materials.
+[[User:ChrisAngove|ChrisAngove]] 17:39, 18 November 2006 (UTC)
+===Acoustic Anechoic chamber?===
-[[John Cage]], a [[20th century]] composer, cited his experience in 1951 in [[Harvard University|Harvard University's]] anechoic chamber &mdash; a room in which he expected to hear nothing, but heard instead what was believed to be the sound of his own bloodflow and nervous system &mdash; as the inspiration for his famous "silent" composition, [[Four Minutes Thirty Three Seconds|''4' 33"'']].
+Why is all the information about acoustic anechoic chambers here in the discussion page rather than in the actual article? <small>—The preceding [[Wikipedia:Sign your posts on talk pages|unsigned]] comment was added by [[Special:Contributions/67.64.252.71|67.64.252.71]] ([[User talk:67.64.252.71|talk]]) 20:41, 13 May 2007 (UTC).</small><!-- HagermanBot Auto-Unsigned -->
-Anechoic chambers for [[electromagnetic radiation]] absorption are used in the aerospace industry for [[radar cross section]] measurement, among other areas.  Anechoic-chamber technology is also used in soundproofing rooms for indoor [[shooting range]]s, and for [[hearing aid]] test chambers.
+===Advertisement?===
-In electromagnetics, anechoic chambers are equipped with [[Electromagnetic absorber materials|absorber material]][http://www.tdkrfsolutions.com/absorbers.htm] to damp the reflection of [[electromagnetic waves]] and are used to measure the properties of antennas or of electronic devices which emit, or are susceptible to interference from, electromagnetic (radio/microwave) energy.  The absorber material is typically pyramidal in shape and made of a carbon-impregnated foam that acts as a resistance, dissipating any energy that strikes it.  These [[Radio Frequency]]/[[Microwave]] anechoic chambers can range in size from a small room to a large airplane hangar, depending on the size of the object to be measured and the frequency range of the radio or microwave signals employed.  Testing can be conducted on full-scale objects, including [[aircraft]], or on scale models where the [[frequency]] of the measuring radiation is scaled up as the size of the object is scaled down.  Most radio-frequency/microwave anechoic chambers are located in a screen room, which is a shielded facility that prevents the leakage of radio-frequency/microwave energy in or out of the chamber, thus ensuring the accuracy of measurements and preventing [[interference]] with outside systems.  Absorber material can be quite flammable and is often protected with an automatic fire-extinguishing system for safety.
+Reference 1 to the TDK RF solutions page seems to lead to a commercial website providing absorption solutions, without really benefiting the article.[[Special:Contributions/46.144.116.121|46.144.116.121]] ([[User talk:46.144.116.121|talk]]) 09:47, 6 August 2014 (UTC)
-Incidentally, electromagnetic anechoic chambers exhibit noticeable degrees of acoustic noise damping in practice, despite great differences in wavelengths between microwave signals and audible (voice) signals.
-== The Radio Frequency Anechoic Chamber ==
+== semi or hemi anechoic  ==
+Hi,
-The internal appearance of the [[radio frequency]] (RF) anechoic chamber is often similar to that of an [[acoustics|acoustic]] anechoic chamber. However, the interior surfaces of the RF anechoic chamber are covered with [[radar absorbent material|radiation absorbent material]] (RAM) instead of acoustically absorbent material.
+I think it would be of interest of many people to add a chapter about semi and hemi anechoic chambers with regard to the different measurement possibilities.  <small>—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/82.210.249.81|82.210.249.81]] ([[User talk:82.210.249.81|talk]]) 09:56, 6 December 2007 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
-===Radiation Absorbent Material===
+Quick reply to this - Semi-anechoic is used to describe RF chambers.  I think hemi describes acoustic, but I have no experience with those.  I have never heard hemi used in relation to RF chambers - EMC enginer  <small>—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/66.41.160.226|66.41.160.226]] ([[User talk:66.41.160.226|talk]]) 01:25, 14 February 2008 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
-RAM is designed to [[absorption (electromagnetic radiation)|absorb]] incident RF radiation in the form of electronmagnetic [[plane wave|plane waves]], also known as [[non-ionising radiation]], as effectively as possible from as many incident directions as possible. The more effectively this is achieved, the less will be the level of RF radiation [[reflection (physics)|reflected]]. Many measurements in the specialist areas of [[electromagnetic compatibility]] (EMC) and antenna [[radiation pattern|radiation patterns]] require that spurious signals from sources, including reflections, are negligible to avoid the risk of causing [[observational error|measurement errors]] and ambiguities. Performing these in an RF anechoic chamber will heavily suppress this source of spurious signals.
+== partly wrong ==
-One of the most effective types of RAM comprises regular arrays of [[pyramid]] shaped pieces, each of which is constructed from a suitably [[attenuation (electronics)|lossy]] material. To work effectively, all internal surfaces of the anechoic chamber must be entirely covered with RAM, though sections of RAM may be temporarily removed to install equipment provided they are replaced before performing any tests. To be sufficiently lossy, RAM can neither be a good [[electrical conductor]] nor a good [[electrical insulator]] as neither type actually absorbs any power. It has to be an intermediate grade of material which absorbs incident power in a controlled way as the incident wave penetrates. Typically pyramidal RAM will comprise a [[rubber|rubberised]] foam impregnated with controlled mixtures of [[carbon]] and [[iron]], depending on the frequency of operation.
+the whole RAM-section contained factual errors, and had no citations or sources: (ferrite plates vs. pyramid shaped is just completely wrong since i know that the ferrite plates are less effective at HIGHER frequencies)
-An alternative type of RAM comprises flat plates, often of [[ferrite (iron)|ferrite]] materials, in the form of flat [[tile|tiles]] fixed to the interior surfaces of the chamber. This type is only effective over a narrower [[band (radio)|frequency band]] than pyramidal RAM and is designed to be fixed to good conductive surfaces, in order to permit a controlled degree of penetration and absorption of the incident wave. It is generally cheaper, easier to fit and more durable than the pyramidal RAM but is less effective at lower frequencies. Its performance might however be quite adequate if tests are limited to the higher RF or [[microwave]] frequencies.
+source: I found a ferrite plate damping curve, but there might be other/better sources.
+There might be more factual errors, since large parts of this article remain unverified.
-===Effectiveness over Frequency===
+<small>—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/194.116.159.61|194.116.159.61]] ([[User talk:194.116.159.61|talk]]) 13:13, 21 January 2008 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
-The overall effectiveness of an RF anechoic chamber is normally determined by its lowest test frequency of operation, at which measured reflections from the internal surfaces will be the most significant compared to higher frequencies. Pyramidal RAM is at its most effective (absorptive) when the incident wave is at [[surface normal|normal]] incidence to the internal surface. The frequency at which it is most effective is when the pyramid height is approximately equal to <math>\lambda/4</math>, where <math>\lambda</math> is the [[free space]] [[wavelength]]. Accordingly, increasing the pyramid height of the RAM for the same (square) base size improves the effectiveness of the chamber at low frequencies but this results both in increased cost and in a reduced unobstructed working volumefor a given chamber size.
+== Caves? ==
-===Installation into a Screened Room===
+Mention if [[cave]]s are good {{PAGENAME}}s, at least electronically. [[User:Jidanni|Jidanni]] ([[User talk:Jidanni|talk]]) 02:26, 22 February 2009 (UTC)
-An RF anechoic chamber is usually built into a screened room, designed using the [[Faraday cage]] principle. This is because most of the RF tests that require an anechoic chamber to minimise reflections from the inner surfaces also require the properties of a screened room to:<br>
-[[attenuation|attenuate]] unwanted signals penetrating inwards and<br>
-prevent leakage from high power tests penetrating outside.<br>
+== Acoustic anechoic chambers ==
-===Chamber Size and Commissioning===
+Is this right: "In general, the interior of an anechoic chamber is very quiet, with typical noise levels in the 10-20 dBA range."  The University of Salford has a semi-anechoic chamber with only [http://www.acoustics.salford.ac.uk/facilities/?content=semianechoic 3.8dba] background noise, so this seems hard to believe. Also, the University of Salford [http://www.acoustics.salford.ac.uk/facilities/?content=anechoic claims] an anechoic chamber with a -12.4dBA background noise level, so perhaps this Guinness record needs updating. I don't really know anything about this topic, but a quick google search yielded these. Anybody know more about this?  <b>[[User:NeverWorker|NeverWorker]]</b> ([[User talk:NeverWorker|Drop me a line]]) 03:27, 29 July 2009 (UTC)
-RF anechoic chambers are typically used to perform [[electromagnetic compatability]] (EMC) tests and [[antenna]] [[radiation pattern|radiation patterns]] measurements. The actual test setups installed usually require extra space than that required to simply house the test equipment, the hardware under test and associated cables. For example, the [[near and far field|far field]] criteria sets a minimum distance between the transmitting antenna and the receiving antenna required when measuring antenna radiation patterns. Allowing for this and the extra space occupied by the pyramidal RAM means that a substantial [[investment|capital investment]] is required into even a modestly dimensioned chamber. For most companies a such an investment in a large RF anechoic chamber is not justifable unless it is likely to be used frequently. It may be rented out during quiet times.
+:The "in general" phrase is correct. Few chambers go lower than 10dBA. The dBA measurement is relatively insensitive to low frequencies, so a low dBA number might be hiding a degree of low frequency rumble. 0dBA is 20 micropascals, or the lowest level a human can hear. Going lower than zero dBA is a very rare achievement. [[User:Binksternet|Binksternet]] ([[User talk:Binksternet|talk]]) 04:01, 29 July 2009 (UTC)
-RF anechoic chambers are normally designed to meet the electrical requirements of one or more accredited standards. Once built, tests are performed during commissioning to verify that the standard(s) are met and a [[certificate]] will be issued, effective for a limited period.
+::A thing I think is missing from the article, is the effect is has on humans. Not only is it quiet; it is so quiet that you can hear the blood run in your veins. The first time I experienced this was in an anechoic sound studio in NRK Marienlyst in Norway. It made me feel quite disconcerted, and some of the women freaked out and got claustrophobia. Also, sounds from others were dampened quite a bit since no sound was allowed to echo, so you felt like you had to yell to be heard even if somebody was right next to you. [[Special:Contributions/80.203.35.234|80.203.35.234]] ([[User talk:80.203.35.234|talk]]) 02:21, 7 April 2013 (UTC)
-===Operational Use===
+== Does this have the frequency culprit reversed??? ==
-Test equipment configurations to be used within RF anechoic chambers must expose as few metallic (conductive) surfaces as possible, other than the actual equipment under test, as these risk causing unwanted reflections. Often this is achieved by using non-conductive [[plastic]], [[composite material|composite]] or [[wood|wooden]] structures for supporting the equipment under test. Where such surfaces are unavoidable, they may be covered with loose pieces of RAM to minimse such reflection as far as possible.
+The sentence:
-A careful assessment of whether to place the test equipment (as opposed to the equipment under test) on the interior or exterior is required. Normally test equipment may be located outside of the chamber provided it is not susceptible to interference from exterior fields which, otherwise, would not be present inside the chamber. This has the advantage of reducing reflection surfaces inside but it requires extra cables to carry the signals including good quality filtering. Unnecessary cables and/or poor filtering can collect interference present externally and conduct it to the inside. A good compromise is to install [[user interfaces|human interface]] equipment (such as [[IBM personal computer|PCs]]), electrically noisy and high power equipment on the outside and the sensitive equipment on the inside.
+"Such risks are from RF or non-ionizing radiation and not from the higher energy ionizing radiation."
+DOES THAT have the culprit reversed? [[Special:Contributions/68.121.32.86|68.121.32.86]] ([[User talk:68.121.32.86|talk]]) 23:03, 29 June 2013 (UTC)
+:It is correct. Risks from high levels of non-ionizing RF include heating (burning or cooking) and electric shocks. It can also affect objects carried such as watches, spectacle frames and heart pacemakers. &mdash; Cheers, [[User:Steelpillow|Steelpillow]] ([[User Talk:Steelpillow|Talk]]) 12:23, 25 October 2015 (UTC)
+== Effect on people remaining within room ==
-One useful application of [[optical fiber|fiber optic]] cables is to provide the communications links to carry signals within the chamber. This is because fiber optic cables are non-conductive and therefore cause negligible reflections.
+No mention of how it produces an unsettling effect and the longest anyone's stayed in one is 45 minutes? Really?  <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/162.157.42.210|162.157.42.210]] ([[User talk:162.157.42.210|talk]]) 05:20, 26 May 2014 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->
-It is normal to [[electronic filter|filter]] [[electric power|electrical power supplies]] for use within the anechoic chamber as unfiltered supplies present a risk of unwanted signals being conducted into and out of the chamber.
+:Me thinks what the article so far has to say about that is quote off: "Anecdotally, some humans may not like such quietness and can become disoriented." It is not anecdotally that it is unsettling. Though I found no medical or otherwise scientific article or research about that per se, it is mentioned in this article: http://www.odditycentral.com/news/worlds-quietest-place-lets-you-hear-your-internal-organs.html : <br>"as it turns out people can’t stand to be in the world’s quietest place for too long. '''The longest a person has lasted in there is 45 minutes.''' [...] The room gets so silent that you can actually hear your internal organs at work. '''And after a while, the hallucinations begin.''' [...] The founder and president of Orfield Labs, Steven Orfield says that people are challenged to sit in the chamber with all the lights out. There was this one reporter who managed to stay in there for 45 minutes. Mr. Orfield himself can do it for 30 minutes, in spite of his mechanical heart valve that becomes very loud inside the room. «When it’s quiet, ears will adapt,» he says. «The quieter the room, the more things you hear. You’ll hear your heart beating; sometimes you can hear your lungs, hear your stomach gurgling loudly. In the anechoic chamber, you become the sound.» '''The experience is so disorienting that it could drive a person mad. In fact, it is imperative that people sit down. Standing up and walking around is simply impossible. Because we orient ourselves through the sounds we hear when we walk, there are no cues to go by inside the chamber.''' «You take away the perceptual cues that allow you to balance and maneuver. If you’re in there for half an hour, you have to be in a chair,» Mr. Orfield says." (emphasis by me) ''And this is about the '''-9dB''' room, not the -21dB room.''<br>
+:So, not being able to stand for a mere 30 minutes, even suggesting  people sit down as quick as possible (" it is imperative that people sit down. Standing up and walking around is simply impossible. Because we orient ourselves through the sounds we hear when we walk") sounds so much more factual than just what the article so far says, as quoted above. ("Anecdotally, some humans may not like such quietness and can become disoriented"). So, while I only found this article on that, and even less info in http://www.mprnews.org/story/2012/04/03/daily-circuit-quiet-room it still, to me, is enough factual data to remove the above quote and insert more about the factual disorienting experience, especially in the dark, also when combined with the everyday action of standing and walking around. [[User:Dietmar Lettau|Dietmar Lettau]] ([[User talk:Dietmar Lettau|talk]]) 17:45, 23 August 2016 (UTC)
+== External links modified ==
-===The Health and Safety Risks associated with the RF Anechoic Chamber===
+Hello fellow Wikipedians,
-There are three significant [[occupational safety and health|health and safety]] risks associated with RF anechoic chambers:<br>
-RF radiation hazard<br>
-Fire hazard<br>
-Trapped personnel<br>
-Personnel are normally excluded from the RF chamber interior during measurements as this can not only cause unwanted reflections from the [[human anatomy|human body]] but also be a possible [[electromagnetic radiation and health|radiation hazard]] to the personnel concerned if tests are being performed at high RF powers. Such risks are from RF or non-ionising radiation, not to be confused with the higher energy [[ionising radiation]].
+I have just modified {{plural:1|one external link|1 external links}} on [[Anechoic chamber]]. Please take a moment to review [https://en.wikipedia.org/enwiki/w/index.php?diff=prev&oldid=717089011 my edit]. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit [[User:Cyberpower678/FaQs#InternetArchiveBot|this simple FaQ]] for additional information. I made the following changes:
-As RAM is absorptive of RF radiation, incident radiation will generate heat within it. If this cannot be dissipated adequately there is a risk that the RAM [[temperature]] may rise to the point of [[combustion]]. This can be a risk if a transmitting antenna inadvertently gets too close to the RAM. Even for quite modest transmitting power levels, high [[antenna gain|gain]] antennas can concentrate the power sufficiently to cause high power [[flux]] near their apertures. Although recently manufactured RAM is normally treated with a [[fire retardant]] to reduce such risks, it is difficult to completely eliminate.
+*Corrected formatting/usage for http://www.npl.co.uk/acoustics/facilities/airborne/ff.html
+When you have finished reviewing my changes, please set the ''checked'' parameter below to '''true''' or '''failed''' to let others know (documentation at {{tlx|Sourcecheck}}).
-Safety regulations normally require the installation of a [[gaseous fire suppression]] system including [smoke detector|smoke detectors]]. Gaseous fire suppression avoids damage caused by the extuinghishing agent which would otherwise worsen damage caused by the fire itself. A common gaseous fire suppression agent is [[carbon dioxide]]. Normally the fire detection system is linked into the power supply to the chamber arranged to disconnect it if smoke or a fire activates the system.
+{{sourcecheck|checked=true}}
-== External links ==
+Cheers.—[[User:Cyberbot II|<sup style="color:green;font-family:Courier">cyberbot II</sup>]]<small><sub style="margin-left:-14.9ex;color:green;font-family:Comic Sans MS">[[User talk:Cyberbot II|<span style="color:green">Talk to my owner</span>]]:Online</sub></small> 17:32, 25 April 2016 (UTC)
+== External links modified ==
-===Suggested Improvements===
+Hello fellow Wikipedians,
-Picture of the interior of an RF anechoic chamber if possible showing something being tested.
-References to the particular international standards (a) that chambers are built to and (b) that are typically tested for in the chambers.
-A picture or two showing the shell construction ie. the screened room for the RF and the 'metre thick cement' or similar for the acoustic one.
-[[User:ChrisAngove|ChrisAngove]] 17:39, 18 November 2006 (UTC)
+I have just modified {{plural:3|one external link|3 external links}} on [[Anechoic chamber]]. Please take a moment to review [https://en.wikipedia.org/enwiki/w/index.php?diff=prev&oldid=744210087 my edit]. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit [[User:Cyberpower678/FaQs#InternetArchiveBot|this simple FaQ]] for additional information. I made the following changes:
-===Acoustic Testing of Satellite Components===
+*Added archive https://web.archive.org/web/20130506144450/http://articles.pubarticles.com/how-to-perfect-your-antenna-testing-1362084935,1137721.html to http://articles.pubarticles.com/how-to-perfect-your-antenna-testing-1362084935,1137721.html
+*Added archive https://web.archive.org/web/20070807231935/http://www.bell-labs.com:80/org/1133/Research/Acoustics/AnechoicChamber.html to http://www.bell-labs.com/org/1133/Research/Acoustics/AnechoicChamber.html
+*Added archive https://web.archive.org/web/20071107061848/http://acs.feld.cvut.cz:80/old/komora.html to http://acs.feld.cvut.cz/old/komora.html
+When you have finished reviewing my changes, please set the ''checked'' parameter below to '''true''' or '''failed''' to let others know (documentation at {{tlx|Sourcecheck}}).
-Does anybody know anything about the very high level acoustic noise testing that used to be done on components to go into space? I believe it may have been to similate launch conditions. Do they still do it or has it been superceeded? The levels would need a heavy duty chamber i think.
-[[User:ChrisAngove|ChrisAngove]] 17:39, 18 November 2006 (UTC)
+{{sourcecheck|checked=false}}
+Cheers.—[[User:InternetArchiveBot|'''<span style="color:darkgrey;font-family:monospace">InternetArchiveBot</span>''']] <span style="color:green;font-family:Rockwell">([[User talk:InternetArchiveBot|Report bug]])</span> 20:06, 13 October 2016 (UTC)
-===Acoustic Anechoic chamber?===
-Why is all the information about acoustic anechoic chambers here in the discussion page rather than in the actual article? <small>—The preceding [[Wikipedia:Sign your posts on talk pages|unsigned]] comment was added by [[Special:Contributions/67.64.252.71|67.64.252.71]] ([[User talk:67.64.252.71|talk]]) 20:41, 13 May 2007 (UTC).</small><!-- HagermanBot Auto-Unsigned -->
-== semi or hemi anechoic  ==
-Hi,
-I think it would be of interest of many people to add a chapter about semi and hemi anechoic chambers with regard to the different measurement possibilities.  <small>—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/82.210.249.81|82.210.249.81]] ([[User talk:82.210.249.81|talk]]) 09:56, 6 December 2007 (UTC)</small><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
-== partly wrong ==
-the whole RAM-section contains factual errors, and no citations or sources: (ferrite plates vs. pyramid shaped is just completely wrong since i know that the ferrite plates are less effective at HIGHER frequencies)
-because of the lack of sources i cannot correct the article myself, and there might be some other mistakes i haven't seen yet.